Several publications and patent documents are cited throughout the specification in order to describe the state of the art to which this invention pertains. Each of these citations is incorporated herein by reference as though set forth in full.
Epidemiological studies have suggested that increased levels of circulating fibrinogen provide an independent predictor of coronary heart disease and in some cases of premature death from cardiovascular disease, although a causative relationship between high levels of fibrinogen and cardiovascular disease has not been firmly established (Wilhelmsen et al. (1984) N. Engl. J. Med., 311:501-505; Kannel et al. (1987) J. Am. Med. Assoc., 258:1183-1186; Thompson et al. (1995) N. Engl. J. Med., 332:635-641; Salomaa et al. (1995) Circulation, 91:284-290).
Fibrinogen is a multifunctional protein essential for hemostasis. It is a 340-kDa glycoprotein, consisting of three non-identical peptide chains Aα, Bβ, and γ, which are linked together by 29 disulfide bonds (Weisel et al. (1985) Science, 230:1388-1391). During coagulation, soluble fibrinogen is converted to insoluble fibrin polymers. The process is initiated by thrombin, a serine protease, which initially catalyzes the cleavage of the two fibrinopeptides from the amino termini of the Aα chains and then two fibrinopeptides from the amino termini Bβ chains. Upon release of the fibrinopeptides, the remaining fibrin monomers aggregate spontaneously to form ordered fibrin polymers (Weisel et al. (1985) Science, 230:1388-1391). The clot is stabilized by the formation of covalent bonds introduced by the action of a transglutaminase, factor XIII (Murthy et al. (1999) Proc. Natl. Acad. Sci. U.S.A., 97:44-48). Under physiological conditions, fibrinolysis is dependent on the binding of circulating plasminogen and tissue-type plasminogen activator (tPA) to fibrin clots. Urokinase and tPA convert plasminogen to the active protease plasmin, which then cleaves fibrin polymers to soluble fragments completing the coagulation and clot resolution cycle.
A major cause of vascular injury leading to the development of atherosclerosis is oxidative stress (White et al. (1994) Proc. Natl. Acad. Sci. U.S.A., 91:1044-1048; Berliner et al. (1996) Free Radic. Biol. Med., 20:707-727; Diaz et al. (1997) N. Engl. J. Med., 337:408-416). Proteins are major targets for reactive species, and nitration of tyrosine residues is a selective protein modification induced by reactive nitrogen species in human disorders as well as animal and cellular models of disease (Ischiropoulos, H. (1998) Arch. Biochem. Biophys., 356:1-11; Turko and Murad (2002) Pharmacol. Rev., 54:619-634). Nitrated proteins have also been detected in atherosclerotic lesions (Beckman et al. (1994) Biol. Chem. Hoppe-Seyler, 375:81-88; Butter et al. (1996) Lab. Investig., 75:77-85; Baker et al. (1999) Arterioscler. Thromb. Vasc. Biol., 19:646-655; Leeuwenburgh et al. (1997) J. Biol. Chem., 272:1433-1436; Cromheeke et al. (1999) Cardiovasc. Res., 43:744-754.